scholarly journals Effect of Different Thermal Schedules on Ductility of Microalloyed Steel Slabs during Continuous Casting

Metals ◽  
2019 ◽  
Vol 9 (1) ◽  
pp. 37 ◽  
Author(s):  
Liu Yang ◽  
Yang Li ◽  
Zhengliang Xue ◽  
Changgui Cheng
Keyword(s):  
Continuous Casting ◽  
Microalloyed Steel ◽  
Tensile Tests ◽  
Microalloyed Steels ◽  
Ferrite Film ◽  
Important Indicator ◽  
Surface Cracking ◽  
Thermomechanical Simulation ◽  
Steel Slabs ◽  
Austenite Grain Boundary

Ductility is the important indicator of transverse surface cracking susceptibility of slabs of microalloyed steels during continuous casting. Welding structure steel HG785 is selected to study the effect of different thermal schedule on ductility of microalloyed steel slabs during continuous casting in this paper. Surface Structure Control (SSC) cooling process parameters of HG785 microalloyed steel were confirmed by the aid of thermomechanical simulation experiment of Gleeble 3500. Results of tensile tests show that the ductilities of slabs under traditional thermal schedule and temperature fluctuation thermal schedule are very low in the III brittleness zone, and the reductions of area reach 29.7% and 26.0% at 800 °C, respectively. The ductility of slabs under SSC thermal schedule is obviously improved, since the pro-eutectoid ferrite film and aggregation of precipitates along the austenite grain boundary has not been discovered.

scholarly journals Effect of Boron on Hot Ductility and Room-Temperature Tensile Properties of Microalloyed Steels with Titanium and Niobium

Materials ◽  
2019 ◽  
Vol 12 (14) ◽  
pp. 2290 ◽  
Author(s):  
Qi Li ◽  
Weijie Liu
Keyword(s):  
Tensile Strength ◽  
Continuous Casting ◽  
Tensile Properties ◽  
Room Temperature ◽  
Thermal Strain ◽  
Tensile Tests ◽  
Rolling Process ◽  
Microalloyed Steels ◽  
Hot Ductility ◽  
Area Reduction

Effect of boron on the hot ductility and room-temperature tensile properties of Ti-Nb-microalloyed steels containing 0.071 wt.% carbon was studied. The thermal stress and thermal strain of continuous casting billets during cooling were simulated via hot tensile tests at the deformation rate of (6 mm/11,000)/s, and the hot ductility of different microalloyed steels was evaluated according to the area reduction of hot tensile specimens. It was found that boron addition was beneficial to improve the hot ductility of continuous casting billets during straightening, and the reduction of area exceeded 60%. The addition of boron, as well as the removal of molybdenum and vanadium, can effectively lower the austenite-to-ferrite transformation temperature and restrain the formation of intergranular ferrite, so as to avoid the brittle zone. Moreover, the room-temperature tensile properties of the steels were explored at different cooling rates after the rolling process. The results showed that as the cooling rate increased from 0.0094 to 0.13 °C/s, the amount of carbonitride precipitate gradually decreased, such as titanium carbide, leading to the relatively low tensile strength. On the other hand, the addition of boron, as well as the removal of Mo and V, promoted the formation of bainite and acicular ferrite, playing an important role in structure strengthening, and compensated for the decrease of tensile strength caused by the low precipitation strengthening.

INFLUENCE OF NITROGEN ON HOT DUCTILITY BEHAVIOR OF MEDIUM CARBON MICROALLOYED STEEL

2009 ◽  
Vol 23 (06n07) ◽  
pp. 1122-1128 ◽  
Author(s):  
SUJUAN ZHAO ◽  
QINGFENG WANG ◽  
ZESHENG YAN
Keyword(s):  
Microalloyed Steel ◽  
True Strain ◽  
Tensile Tests ◽  
Microalloyed Steels ◽  
Hot Ductility ◽  
True Strain Rate ◽  
Medium Carbon ◽  
Ductility Trough ◽  
Carbon Microalloyed

The current study aims to estimate the influence of enhanced nitrogen on the hot ductility of medium carbon microalloyed steel. For this purpose, hot tensile tests were carried out at temperatures rangeing from 700°C-1000°C at a true strain rate of 0.001s-1. The fracture surfaces and their neighboring precipitates and matrix microstructures "frozen" in tensile temperatures were observed. The dependence of hot ductility on the fracture mode and in situ microstructural changes were discussed. The results indicate that raising the nitrogen content from 0.003% to 0.014% and 0.021% was found to deteriorate the ductility as the obtained ductility trough became deeper and wider. The trough deepening caused by the addition of nitrogen was due to the formation of film-like ferrite and fine VN precipitation along the austenite grain boundaries promoting low ductility intergranular failure. On the other hand, the retarded dynamic recrystallization, the promoted deformation induced ferrite formation and precipitation at higher temperatures by enhanced nitrogen were regarded as the possible reasons for a wider trough. In summary, the above results indicate the hot ductility of medium carbon microalloyed steels is weakened to some extent by enhanced nitrogen and their windows suitable for continuous casting should be schemed very carefully.

Formation and Control of Transverse Corner Cracks in the Continuous Casting Slab of a Microalloyed Steel

2021 ◽  
pp. 2000649
Author(s):  
Yadong Wang ◽  
Qiang Ren ◽  
Lifeng Zhang ◽  
Xiaogang Yang ◽  
Wen Yang ◽  
...  
Keyword(s):  
Continuous Casting ◽  
Microalloyed Steel ◽  
Continuous Casting Slab ◽  
Corner Cracks ◽  
And Control

scholarly journals Effects of deformation on the microstructure of a Ti-V microalloyed steel in the phase transition region

2004 ◽  
Vol 57 (4) ◽  
pp. 303-311
Author(s):  
Wiliam Regone ◽  
Sérgio Tonini Button
Keyword(s):  
Phase Transition ◽  
Phase Transformation ◽  
Transition Region ◽  
Microstructural Evolution ◽  
Microalloyed Steel ◽  
Hot Forging ◽  
Microalloyed Steels ◽  
Air Cooling ◽  
Water Cooling ◽  
Phase Transition Region

Microalloyed steels are used in the forging of many automotive parts like crankshafts and connecting rods. They are hot worked in a sequence of stages that includes the heating to the soaking temperature, followed by forging steps, and finally the controlled cooling to define the microstructure and mechanical properties. In this work it was investigated the thermomechanical behavior and the microstructural evolution of a Ti-V microalloyed steel in the phase transition region. Torsion tests were done with multiple steps with true strain equal to 0.26 in each step. After each torsion step the samples were continuous cooled for 15 seconds to simulate hot forging conditions. These tests provided results for the temperature at the beginning of the phase transformation, and allowed to analyze the microstructural changes. Also, workability tests were held to analyze the microstructural evolution by optical and scanning electron microscopy. Results from the torsion tests showed that the temperature for the beginning of phase transformation is about 700 ºC. Workability tests held at 700 ºC followed by water-cooling presented microstructures with different regions: strain hardened, and static and dynamic recrystallized. Workability tests at 700 ºC followed by air-cooling showed a complex microstructure with ferrite, bainite and martensite, while tests at 650 and 600 ºC followed by water-cooling showed a microstructure with allotriomorphic ferrite present in the grain boundaries of the previous austenite.

Impact of Surface Structure Control Cooling During Continuous Casting on Hot Ductility of Microalloyed Steel

2015 ◽  
Vol 87 (7) ◽  
pp. 871-879 ◽  
Author(s):  
Martin Lückl ◽  
Ozan Caliskanoglu ◽  
Sergiu Ilie ◽  
Jakob Six ◽  
Ernst Kozeschnik
Keyword(s):  
Continuous Casting ◽  
Surface Structure ◽  
Microalloyed Steel ◽  
Hot Ductility ◽  
Structure Control

Continuous casting technology of hot cycle operations of tundish for clean steel slabs

1998 ◽  
Vol 95 (10) ◽  
pp. 1273-1286 ◽  
Author(s):  
H. Uehara ◽  
H. Osanai ◽  
J. Hasunuma ◽  
K. Hara ◽  
T. Nakagawa ◽  
...  
Keyword(s):  
Continuous Casting ◽  
Clean Steel ◽  
Casting Technology ◽  
Steel Slabs

scholarly journals Tundish Nozzle Constriction in Continuous Casting of Titanium Bearing Stainless Steel Slabs

1984 ◽  
Vol 70 (14) ◽  
pp. 1704-1711 ◽  
Author(s):  
Morihiro HASEGAWA ◽  
Shigeaki MARUHASHI ◽  
Yoshioki KAMIDATE ◽  
Yutaka MURANAKA ◽  
Fumio HOSHI
Keyword(s):  
Stainless Steel ◽  
Continuous Casting ◽  
Steel Slabs
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